The JIT no longer performs loop unrolling if the loop compiles to too much code.

Build cffi import libraries as part of translation by monkey-patching an
additional task into translation

Use a compact strategy for Python lists that mix integers and floats,
at least if the integers fit inside 32 bits. These lists are now
stored as an array of floats, like lists that contain only floats; the
difference is that integers are stored as tagged NaNs. (This should
have no visible effect! After lst=[42,42.5], the value of
lst[0] is still not the float 42.0 but the integer 42.)